Natural Disaster

The Mission:

Students will be able to understand how tracking wind speeds and reading weather reports help them to track the weather and predict cyclonic activities. Students are expected to create game where a user is expected to track the weather report and predict the cyclone. This helps the user to state or release the safety measure.

2. Concepts to understand:

2.1 Weather and Climate

In our day to day life, we may have come across common terminologies like weather and climate. These to terminologies may sound the same in terms of the information they convey about, but they are very different.

2.1.1 Weather

A weather of a place is basically the condition of the atmosphere outside our home and in our surrounding. For example, if you go out on a very sunny day, you may say it is 35 °C hot outside. Similarly, when you see the weather forecast news in your television, you are able to see the weather prediction for some days or a week in the news channel. Hence, weather is a state of atmosphere of different places in a short period of time (hours, days, week etc.). Weather is described by temperature, air pressure and humidity.

2.1.2 Climate

Climate is basically the average of the weather conditions over a region in a long span of time period. It’s basically a long-term weather average of the weather patterns in a given place or a region. Generally, a climate analysis is done after more than 30 years of observations of the weather patterns in that location.

2.2 Air pressure and wind patterns

Air around us has mass. The envelope of air surrounding us is called atmosphere. Air exerts pressure due to its weight. This pressure is called atmospheric pressure or simply air pressure.

Following factors affects the

air pressure:

1. Change in temperature
2. Amount of humidity (water vapour) in atmosphere
3. Uneven heating of land and water
4. Altitude

Change in any of these factors affects atmospheric pressure. Air pressure varies in indirect proportion with the change in temperature and is in direct proportion to amount of humidity in air. If atmospheric temperature decreases, then the air becomes dense and hence, the atmospheric pressure increases. If amount of humidity in air increases, then the air density increases as a result of increase in the air pressure. Due to uneven heating of land, zones with different in air pressure are created. As a result, air moves from region of high air pressure to the region of low air pressure. This moving air is called wind. A gentle wind is called breeze, whereas, a fast-moving wind is called gale.

2.3. Uneven heating of land and water

During the daytime, water from the ocean evaporates and gets added into the air as moisture due to heat of the Sun. Thus, the water content in air above the ocean increases. Moisture content in the air above the land is relatively very low.

Moist air is heavy compared to dry air. Hence, moist air heats up relatively very slowly compared to the dry air. During the day, the land near equator heats faster compared to the water in the ocean. The air above the land heats much faster compared to air over ocean. This results in the creation of low air pressure zone over the land and high air pressure zone over the oceans. This moisture rich air then moves from oceans towards the land.

The rate of evaporation increases during summer and more moisture is added into air. Due to uneven heating of land and ocean, a huge difference in air pressure is created. The moist air moves towards the land near equator and these winds are called the monsoon winds. These winds bring rain and sometimes accompany with strong winds. This may result in natural disaster like cyclones and thunderstorms. Let us learn about thunderstorms.

2.4 Thunderstorms and Cyclones

Thunderstorms develop very frequently in hot, humid and tropical regions like India. Due to the high temperature, air on land heats up faster and rise. It carries high concentration of moisture with it. Due to low temperature at high altitude, the moisture in the air cools and converts into water droplets. These water droplets merge together to make bigger water droplets. As weight of these droplets increases, they fall down on the earth in the form of rain.

The cycle of rapid movement of hot moist air rising up and falling water droplets, creates lightning and thunderclaps. This event is called thunderstorm.

2.4.1 How to predict a Thunderstorm?

Thunderstorms are most likely to form in an area where average temperature and humidity remains higher for very long period of days. Thunderstorms are frequently sighted along coastal areas.

In order to predict thunderstorm in coastal regions, one must keep track of these things for period of 2 weeks.

• Minimum and maximum temperature of day
• Amount of precipitation in air
• Average wind speed during daytime and at evening

If the readings are constant or increase over the period of time, then thunderstorms are more likely to develop in those areas.

2.4.2 Cyclone

Water turns to vapour by absorbing heat. The collective concentration of vapour in the air is termed as moisture. When moisture in air at higher altitudes cools to form water droplets, and releases heat, the air at higher altitudes heats up and rises. This results in low air pressure and cause more air from land to rise rapidly. If this cycle continues during thunderstorm, then storm develops into cyclone. During the cyclone, the wind speed can reach the speed of 300 km/hr. During the development of storm, more air moves towards the centre of storm and the cycle repeats. This results in formation of low air pressure zone in the middle and high-speed winds revolving around the centre. This weather condition is called as cyclone.

2.4.3 How to predict a Cyclone?

Cyclones are most likely to develop around the coastal area where moisture content in air remains higher and strong winds develop.

Cyclones are destructive in nature due to following reasons.

• Heavy rains and high-speed winds accompany cyclones.
• Heavy rain can cause flood like condition in area hit by cyclone.
• The high-speed wind can cause damage to buildings, trees, phone lines, electric pole, telephone lines, etc. causing tremendous loss to life and property.
• Cyclone lifts the water from the ocean as high as 3-12 metres. This water is stored in the centre of the cyclone.
• When the cyclone hits the shore, the water from the cyclone is dumped on the land and it cause flood like situation, resulting in reduced soil fertility.
• Floods can cause severe loss of life and damages property, crops, etc.

Effective safety measures during cyclone.

• Fishermen are warned not to enter oceans for fishing during cyclone like conditions
• Rapid warnings are given to the ports so that ships are anchored or escorted to deep water before the cyclone hits the port.
• One should take the warning issued by government seriously and vacate the area of residence if instructed.
• Do not touch electrical circuits or water taps. Do not take shower.